Both the derailleur and derailleur hanger broke and got caught in the wheel. It happened at very low speed in a parking lot. Of course, I stopped immediately to inspect.
What worries me: the paint was visibly chipped around the axle insert due to contact with the bent derailleur. I’ve since applied touch-up paint. It looks cosmetic and I’ve seen the paint react similarly to other small chips but I can’t stop overthinking it.
Any insights would be appreciated. How likely is it that the chainstay is structurally compromised?
by Knightfall_
2 Comments
How did the hanger break at low speed? If I were to guess, seems like a wheel or chain wasn’t installed properly and significant torque was applied via pedaling at low speed?
Have you tried removing the wheel and checking alignment with the axle? That gouge looks deep and carbon fiber isn’t forgiving, especially around load bearing areas. I’d be most concerned that the axle insert is misaligned or damaged.
I’m not certain of the specific thing you’re concerned about, and if this picture is after touch up paint then it’s harder to comment on the appearance since any potential damage is now obscured.
In regards to potential structural damage from the derailleur hanger breaking and what now looks like some gouges from the frame. There’s probably some different opinions on this, because at the end of the day this is a question of probabilities really. It largely depends on what the frame is made of. If it’s aluminium there will be those that say the frame might be weakened/fatigued and therefore more prone to breaking later. This is a possibility but definitely not a certainty, and personally I would say its not an issue. If it’s steel it’s fine (at least from what’s evident in this photo). If it’s carbon then that’s where the risk is much higher. Given your derailleur hanger appears to be carbon, I’m guessing the frame is too.
It looks like chipped paint and some superficial gouging. The fact that the paint is not cracked is a reassuring sign that there hasn’t been a significant change in alignment or anything to caused significant delamination. As this would definitely suggest impending failure. There is a risk that if those chips extend to the frame there could be some loss of structural integrity. But from what I can see it doesn’t appear significant.
If it’s carbon I would be very careful with applying anything on the exposed frame unless you’re absolutely certain it’s safe for carbon fibre. Most paints contain a solvent like acetone to keep the paint in a liquid solution, and this can dissolve the resin in the carbon fibre resulting in delamination. If you’re applying it to gouges this is even more risky as it’ll penetrate multiple layers.
Overall we’d need a bit more information about your bike/frame. But at the end of the day no one on the internet can say 100% that your bike is perfectly fine if it is a carbon frame.